摻雜氧化鋅奈米微晶之表面穩定強誘電性液晶元件的分子排列與電性研究

Abstract

在液晶物理的研究上及與液晶元件的發展上，時常藉著摻雜奈米結構粒子來改善液晶的分子排列與響應速度。本論文以摻雜氧化鋅奈米微晶之表面穩定強誘電性液晶(或稱鐵電相液晶)元件為研究樣本，利用影像式偏光量測系統、電容－電壓曲線、時析電光響應與時析偏振傅立葉轉換紅外光譜等量測方法，針對分子排列、光學特性、電性及外加驅動電壓下之動態響應，將摻雜氧化鋅奈米微晶之鐵電相液晶與未摻雜之鐵電相液晶相互對照。我們發現摻雜氧化鋅奈米微晶後之表面穩定鐵電相液晶，其整體液晶分子有較好的排列分布，且在無外加電場下可提升其光穿透率達2.27倍；此外，摻雜氧化鋅奈米晶體後之鐵電相液晶在外加相同驅動電場下，比未摻雜之強誘電性液晶元件反應速度快2倍。對於動態電光時析響應、二維相關光譜分析與鐵電相液晶的分子官能基排列與動態行為間的關係有深入的研究與討論。

In order to improve the electro-optical properties and response time of FLC material, doping with nanostructured materials is a newly developed technique to achieve the goal. In this thesis, we compare electrical properties and electro-optical dynamics of the surface-stabilized ferroelectric liquid crystal (SSFLC) with doping of ZnO nanocrystals (nc-ZnO) and without doping. We use several kinds of techniques, including imaging polarimetry, C-V hysteretic characterization, time-resolved electro-optical response and time-resolved FTIR, to analyze the above mentioned properties. We find that the nc-ZnO doping can improve the azimuthal and the polar alignments of FLC by reducing the full-width-and-half-maximum (FWHM) width. The approach readily improves the optical transmission property of FLC by 2.27 times at no applied field and reduces the switching time of the electro-optical response by a factor of 0.5. By using 2D IR correlation, we discovered that ZnO nanocrystals produce a novel binding effect on sub molecular fragments of FLC molecules, which lead to an improved LC alignment quality in both steady-state and dynamic processes.